All-solid lithium battery and method of manufacturing same

Abstract

Provided is an all-solid lithium battery including: a low-angle oriented positive electrode plate that is a lithium complex oxide sintered plate having a porosity of 10 to 50%; a negative electrode plate containing Ti and capable of intercalating and deintercalating lithium ions at 0.4 V or higher (vs. Li/Li+); and a solid electrolyte having a melting point lower than the melting point or pyrolytic temperature of the oriented positive electrode plate or the negative electrode plate, wherein at least 30% of pores in the oriented positive electrode plate is filled with the solid electrolyte in an observation of a cross-section perpendicular to a main face of the oriented positive electrode plate.

What is claimed is: 
     
       1. An all-solid lithium battery comprising:
 an oriented positive electrode plate that is a lithium complex oxide sintered plate having a porosity of 10 to 50%, wherein the lithium complex oxide sintered plate contains a plurality of primary grains composed of lithium complex oxide, and the primary grains are oriented at a mean orientation angle of more than 0° to 30° to a main face of the oriented positive electrode plate; 
 a negative electrode plate that is a sintered plate containing Ti and capable of intercalating and deintercalating lithium ions at 0.4 V or higher (vs. Li/Li + ); and 
 a solid electrolyte having a melting point lower than a melting point or pyrolytic temperature of the oriented positive electrode plate or the negative electrode plate, wherein at least 30% of pores in the oriented positive electrode plate is filled with the solid electrolyte in an observation of a cross-section perpendicular to a main face of the oriented positive electrode plate. 
 
     
     
       2. The all-solid lithium battery according to  claim 1 , wherein the melting point of the solid electrolyte is higher than an operational temperature of batteries and is 600° C. or lower. 
     
     
       3. The all-solid lithium battery according to  claim 1 , wherein the solid electrolyte is represented by a formula xLiOH·yLi 2 SO 4 , where x+y=1, and 0.6≤x≤0.95. 
     
     
       4. The all-solid lithium battery according to  claim 1 , wherein the solid electrolyte comprises at least one selected from the group consisting of Li 3 OCl, Li (3-x) M x/2 OA, where 0≤x≤0.8, M is at least one selected from the group consisting of Mg, Ca, Ba and Sr, and A is at least one selected from the group consisting of F, Cl, Br and I, Li 2 (OH) 1-a F a Cl, where 0≤a≤0.3, and Li 2 OHX where X is Cl and/or Br. 
     
     
       5. The all-solid lithium battery according to  claim 1 , wherein the solid electrolyte is represented by a formula Li a (OH) b F c Br, where 1.8≤a≤2.3, b=a−c−1, and 0.01≤c≤0.11 and comprises an antiperovskite crystal phase. 
     
     
       6. The all-solid lithium battery according to  claim 1 , wherein at least 70% of the pores in the oriented positive electrode plate is filled with the solid electrolyte. 
     
     
       7. The all-solid lithium battery according to  claim 1 , wherein at least 30% of an outer peripheral length of pores in the oriented positive electrode plate is in contact with the solid electrolyte in an observation of a cross-section perpendicular to a main face of the oriented positive electrode plate. 
     
     
       8. The all-solid lithium battery according to  claim 7 , wherein at least 50% of the outer peripheral length of pores in the oriented positive electrode plate is in contact with the solid electrolyte. 
     
     
       9. The all-solid lithium battery according to  claim 1 , wherein at least 20% of planes other than the (003) plane of the lithium complex oxide is in contact with the solid electrolyte at the surface of pores in the oriented positive electrode plate in an observation of a cross-section perpendicular to a main face of the oriented positive electrode plate. 
     
     
       10. The all-solid lithium battery according to  claim 9 , wherein at least 30% of planes other than the (003) plane of the lithium complex oxide is in contact with the solid electrolyte at the surface of pores in the oriented positive electrode plate. 
     
     
       11. The all-solid lithium battery according to  claim 1 , wherein the negative electrode plate has a porosity of 2 to 40%. 
     
     
       12. The all-solid lithium battery according to  claim 11 , wherein at least 30% of pores in the negative electrode plate is filled with the solid electrolyte in an observation of a cross-section perpendicular to a main face of the negative electrode plate. 
     
     
       13. The all-solid lithium battery according to  claim 12 , wherein at least 70% of pores in the negative electrode plate is filled with the solid electrolyte. 
     
     
       14. The all-solid lithium battery according to  claim 11 , wherein at least 30% of an outer peripheral length of pores in the negative electrode plate is in contact with the solid electrolyte in an observation of a cross-section perpendicular to a main face of the negative electrode plate. 
     
     
       15. The all-solid lithium battery according to  claim 14 , wherein at least 50% of the outer peripheral length of pores in the negative electrode plate is in contact with the solid electrolyte. 
     
     
       16. The all-solid lithium battery according to  claim 1 , wherein the solid electrolyte is a melt-solidified material of xLiOH·yLi 2 SO 4 , where x+y=1, and 0.6≤x≤0.95. 
     
     
       17. The all-solid lithium battery according to  claim 1 , wherein the solid electrolyte is at least one melt-solidified material selected from the group consisting of Li 3 OCl, Li (3-x) M x/2 OA, where 0≤x≤0.8, M is at least one selected from the group consisting of Mg, Ca, Ba and Sr, and A is at least one selected from the group consisting of F, Cl, Br and I, Li 2 (OH) 1-a F a Cl, where 0≤a≤0.3, and Li 2 OHX, where X is Cl and/or Br. 
     
     
       18. The all-solid lithium battery according to  claim 1 , wherein the solid electrolyte is a melt-solidified material that is represented by a formula Li a (OH) b F c Br, where 1.8≤a≤2.3, b=a−c−1, and 0.01≤c≤0.11 and comprises an antiperovskite crystal phase. 
     
     
       19. The all-solid lithium battery according to  claim 1 , which is charged and discharged at a temperature of 100° C. or higher. 
     
     
       20. The all-solid lithium battery according to  claim 1 , further comprising spacers that define the thickness of the solid electrolyte layer between the oriented positive electrode plate and the negative electrode plate. 
     
     
       21. The all-solid lithium battery according to  claim 20 , wherein the spacers have an electrical resistivity of 1×10 5  Ω·cm or more. 
     
     
       22. The all-solid lithium battery according to  claim 20 , wherein the spacers are composed of ceramic. 
     
     
       23. A method of producing the all-solid lithium battery according to  claim 1 , comprising the steps of:
 placing solid electrolyte powder having a melting point lower than the melting point or pyrolytic temperature of the oriented positive electrode plate or the negative electrode plate on one of the oriented positive electrode plate and the negative electrode plate; 
 placing the other of the oriented positive electrode plate and the negative electrode plate on the solid electrolyte powder; 
 pressing the negative electrode plate toward the oriented positive electrode plate, or the oriented positive electrode plate toward the negative electrode plate at 100 to 600° C. to melt the solid electrolyte powder and permeate the melt into the pores in the oriented positive electrode plate and/or the negative electrode plate; and 
 spontaneously or controllably cooling the oriented positive electrode plate, the molten electrolyte and the negative electrode plate to solidify the molten electrolyte. 
 
     
     
       24. The method according to  claim 23 , wherein the all-solid lithium battery includes spacers that define the thickness of the solid electrolyte layer between the oriented positive electrode plate and the negative electrode plate, and the spacers are sandwiched along with the solid electrolyte powder between the oriented positive electrode plate and the negative electrode plate in the step of placing the negative electrode plate or the positive electrode plate on the solid electrolyte powder.